If we just preordered the phone, how will we find the IMEI or HEX MEID? Is it supposed to show on the receipt or do we sit and wait until we have it in our hands?

Yup, until you receive the actual unit you can't know which device you're assigned. Basically the company you bought this from has a bunch of phones available and takes the first box they have on hand when preparing your order for shipping, you don't get an actual, specific unit assigned when you order.

Yup, until you receive the actual unit you can't know which device you're assigned. Basically the company you bought this from has a bunch of phones available and takes the first box they have on hand when preparing your order for shipping, you don't get an actual, specific unit assigned when you order.